Meeting Abstract
Advancements in imaging techniques have drastically improved our ability to visualize, study, and share complex, often minute, anatomical relationships. The recent adoption of soft-tissue X-ray imaging tools, such as diffusible iodine-based contrast-enhanced computed tomography (diceCT), is beginning to offer previously unattainable insights into the configurations of soft-tissue complexes across Metazoa. As a contrast agent, dissolved iodine diffuses deeply to bind fats and carbohydrates that are naturally present throughout metazoan soft tissues, predictably altering tissue densities. Like the current gold standard, magnetic resonance imaging (MRI), diceCT does not require physical dissection and can differentiate between the lipid content of myelinated versus non-myelinated tissues, offering great potential for neuroanatomical studies. This is especially true for small specimens (e.g., embryos and neonates of nearly all taxa, adults of diminutive forms), which require resolutions of < 25 µm to image clearly—well below the typical 100–250 µm scales of MRI. Within the brain, diceCT distinguishes myelinated fiber tracts from unmyelinated cortices, nuclei, and ganglia, and allows 3-D visualization of their anatomical interrelationships at previously unrealized resolutions. In this study we illustrate the utility of diceCT for the rapid visualization of both external and internal brain anatomy in vertebrates—alongside cranial osteology, complete peripheral nerve pathways, and targets of innervation. We demonstrate its transformative potential for developing high-resolution, neuroanatomical datasets and describe best practices for imaging large numbers of specimens for evolutionary study and broad data sharing.
